The extraction and analysis of tissue samples has proven a highly effective procedure for identifying cancer, pre-malignant conditions and other infections. This procedure has proven particularly effective for identifying pre-invasive cervical lesions, the treatment of which is usually highly successful.
Before using a biopsy device to extract and analyze cervical tissue, a doctor will typically conduct an initial screening procedure known as a Pap smear. This screening procedure involves rotating a swab, cytobrush or spatula along the portio cervix or vaginal mucosa to obtain a cell sample which is then spread on a clear slide and analyzed. If the cells appear atypical with dysplastic features, or reflect low-grade or high-grade intraepithelium lesions, then a tissue biopsy is usually required.
The most common biopsy device currently used for cervical tissue extraction is a punch biopsy. In order to obtain a tissue sample, a practitioner observes the tissue through a colposcope, which magnifies the tissue, and then uses the punch biopsy to grasp a portion of tissue and extract it. Major drawbacks of the punch biopsy are that it may cause tissue trauma, disfigurement of the cervix and significant pain. Further, the difficulty in simultaneously using two separate instruments, i.e., viewing the tissue through the colposcope while trying to manipulate the punch biopsy, often results in an inadequate specimen. As a result, practitioners often grasp a larger portion of the tissue than necessary to ensure that an adequate specimen is retrieved. This may result in excessive bleeding requiring cauterization.
U.S. Pat. No. 4,461,305, herein incorporated by reference, discloses a biopsy device comprising a generally cylindrical core-cutter with a rotatably mounted cutting blade. A plunger, slidably mounted within the core-cutter, is used to limit the depth to which the core cutter advances into the tissue to thereby provide greater control over the sample size. The plunger also provides a means to eject the severed sample. However, it is still possible for the device to penetrate excessively into the tissue.
U.S. Pat. No. 4,976,269 to Mehl, herein incorporated by reference, discloses a tissue needle for extracting a biopsy sample having a stylet, with a sharp tip, a cavity (sample notch) near the tip, a tubular cannula which is spring loaded, and a trigger in a handle. It does not show any means to limit the depth of penetration of the stylet or cannula into tissue.
In addition, the foregoing devices are designed for reuse, which is a major drawback in today's society where the use of contaminated needles has significantly contributed to the spread of diseases.
Accordingly, the need exists to provide an improved device and method for obtaining tissue samples which reduces the amount of pain and bleeding experienced by a patient.